Prader-Willi syndrome is a genetic disease (lack on chromosome 15) that creates a decrease in muscle tone, sex hormones and appetite control, the latter resulting in a tendency to obesity. Other signs such as short stature, underdeveloped sex organs, motor and learning difficulties, and a predisposition to diabetes are also recognized. It was described in the mid-twentieth century by Swiss physicians Andrea Prader and Heinrich Willi, among others.
